@jkandasa the gateway is stateless, it has no concept of queue.

@jkandasa I just finished a Gateway build with TinyGSM. You can find it here: https://www.openhardware.io/view/567/MySensors-GSM-Gateway

@GertSanders I think there is a better chance that the controller is going to be online. I have a mini UPS on my RPi for example if there are no mains supply. I also have a device pinging the controller and if it is not responding sending the halt/reboot signal to the RPi. If your node is working an a universal GSM gateway, that's a different story though. But does it have a power (battery) backup in case there is a blackout ?